I'm like Rick...saw it listed somewhere...actually following up on another thread where this was discussed... and I thought it was prohibitive for a one inch square.

As far as substitutes go... see a thread I started below about yak hair...JC and I got to fooling around and the thread died but I think it was because probably no one has had real experience comparing the two. They sure look similar to me in the sunlight ..PB may be just a little more translucent.
In the "tight lines fly fishing" link by Crotalus they have yak hair and tout it in the place of PB.